Early learning has been difficult to study because of the limited behavioral repertoire of infants and lack of suitable rewards and reinforcements. Our emerging understanding of the development of ingestion in rat pups now provides a behavioral and motivational system with which to examine appetitive learning in infants, and in particular, the factors influencing food-related reward or reinforcement. We will study: (1) environmental determinants of early learning and how they change with the age; (2) the relative contributions of nutritional and sensory deprivation to the value of food reward; and (3) the relationship between behavior during training and the strength of early learning. Our recent findings that preference for an odor can be trained unilaterally (with one naris open), provides opportuniies to further examine mechanisms in simple forms of learning. We will examine (4) behavioral aspects of the phenomenon of unilateral olfactory preference conditioning first, and then (5) the neural basis of this form of olfactory conditioning. For the latter, we will use selective lesions of olfactory structures, and metabolic mapping of neural activity with deoxyglucose autoradiography. Our proposed investigations are based on the conceptualization of early appetitive learning as one aspect of a broader system of ingestive behavior and provide an ontogenetic analysis of early learning in which behavioral and neural development can be examined and integrated.